Quize 2 Flashcards
what does the silane coupling agent do
without it the wear resistance is cut in half
what has more wear resistance
Microhybrid
what has the most shrinkage
microfill
microfills in regard to filler material and polymer matrix
less filler
more polymer
microfill will _____ more _____
absorb, water
microfill will have a _____ surface
softer
what type of material do you use when concerned with esthetics
microfilled
what numbers represent round burrs
1/4th through 8 (will probably be four)
what implications does a negative rake angle have
rake face is ahead of the radius
In the fisher burr, increased clearance causes?
decreased edge
in the fisher burr, increase rake causes
increased edge
what is the effect of the coefficient of thermal expansion on microhybrids on microcomposits
microfilled has more polymer which means more expansion
most common photo absorbing material
camphorquinone (blue range 460 - 470)
Irradiance
number of photons per second emmited by the light source
energy
flux times time
energy density
irradiance times time
what is the purpose of etching
forms macro and micro tags
removes smear layer
(removes hydroxy apatite from outer dentin, exposes collagen sponge later, exposes dentin tubules, frosty apearance)
importance of collagen later in the tooth and why we do not dry it our
if it dries, it collapses on itself
which would prevent penetration by the primer and bonding will fail
what is the hybrid layer and the bonding technique
impregnation of the etched dentin by the resin in the primer
formed by the primer
components of all bonding systems
- conditioner (etch)
- Primer
- Adhesive (bonding)
components of composite material
- polymer matrix
- filler perticles
- coupling agents
- initiator-accelerator system
where is HEMA found
In the primer
what does the HEMA molecule look like
nydrophobic (bonding agent) and hydrophilic (dentin) ends (bi-functional monomer)
reciprocity
increased radiance = decreased time
where would you find the most inreacted double carbon bonds in a cured carbon restorative material
Air inhibited surface layer
composite restorative materials are polymerized by what polymerization process
free radical polymerization
